Transcription-dependent and -independent signaling of RSK2 in cancer metastasis

肿瘤转移是一个复杂的生物学过程，涉及多种信号通路。因此，单个代理 通常是不够的，并且联合治疗在转移性癌症的成功治疗中是至关重要的。 我们报道了p90核糖体S6激酶2（RSK 2）通过激活多个下游信号通路促进肿瘤转移。 印刷受体.此外，我们最近发现，谷氨酸脱氢酶1（GDH 1），一个关键的酶，在 腺苷酸氨解途径，通过激活CamKK 2及其下游AMPK提供抗失巢凋亡信号， 调节能量产生，保护细胞免于失巢凋亡，促进肺癌转移。的影响 GDH 1在LKB 1缺陷型癌症中是明显的，其中AMPK活化主要依赖于CamKK 2。这 表明RSK 2和GDH 1是有希望的抗转移靶点。事实上，通过factors靶向RSK 2或GDH 1， （由我们的合作者UCSF的Jack汤顿鉴定）或R162（由我们的小组鉴定）减弱转移。 我们最近发现，这两个不同的信号轴的遗传或药理学抑制导致 LKB 1缺陷型肺癌细胞侵袭、迁移和失巢凋亡抗性协同减弱 生物学和代谢研究表明，联合治疗进一步减弱CREB激活。 有趣的是，GDH 1敲低导致CREB的另一种上游激酶CamK 4的活性降低， 这表明RSK 2和GDH 1的联合靶向可能通过抑制RSK 2而进一步减弱CREB活性， GDH 1-CamKK 2-CamK 4信号通路参与CREB磷酸化。此外，RSK 2的组合靶向 在表达LKB 1野生型（wt）的细胞和RSK 2的细胞中， 磷酸化LKB 1，导致AMPK激活。这些数据表明，RSK 2可能通过LKB 1发出信号， AMPK有助于LKB 1 wt细胞中的失巢凋亡抗性。 因此，我们假设RSK 2和GDH 1在转录过程中协调调节AMPK和CREB。 依赖性和非依赖性方式来提供癌细胞中的促转移潜能。因此， 通过RSK 2和GDH 1抑制剂的组合的细胞和代谢信号传导是有希望的抗转移剂。 治疗策略我们将使用LKB 1或LKB 1缺失的肺癌作为研究平台。三个具体目标 提出：（1）为了证明RSK 2和GDH 1是否协调地提供抗失巢凋亡保护， 通过分别通过LKB 1和CamKK 2激活AMPK，以检测RSK 2和 GDH 1通过激活CREB和CREB转录靶点共同介导迁移和促侵袭信号; (3)为了验证RSK 2和GDH 1信号传导是否与患者肿瘤中的转移潜能相关， 评估靶向RSK 2和GDH 1组合治疗转移性癌症的疗效。

Metastasis is a complex biological process, which involves multiple signaling pathways. Therefore, a single agent is often insufficient and combination therapy is vitally important in the successful treatment of metastatic cancer. We reported that p90 ribosomal S6 kinase 2 (RSK2) promotes metastasis by activating multiple downstream substrates. In addition, we recently identified that glutamate dehydrogenase 1 (GDH1), a critical enzyme in the glutaminolysis pathway, provides anti-anoikis signals by activating CamKK2 and its downstream AMPK to regulate energy production, protecting cells from anoikis, and promoting metastasis in lung cancer. The effect of GDH1 is evident in LKB1-deficient cancer, where AMPK activation predominantly depends on CamKK2. This suggests that RSK2 and GDH1 are promising anti-metastasis targets. Indeed, targeting RSK2 or GDH1 by fmk (identified by our collaborator Jack Taunton at UCSF) or R162 (identified by our group) attenuated metastasis. We recently found that genetic or pharmacological inhibition of these two distinct signaling axes results in synergistic attenuation of cell invasion, migration, and anoikis resistance in LKB1-deficient lung cancer. Biological and metabolic studies revealed that the combined therapy further attenuates CREB activation. Intriguingly, GDH1 knockdown resulted in decreased activity of CamK4, another upstream kinase of CREB, suggesting that combined targeting of RSK2 and GDH1 may further attenuate CREB activity by inhibiting RSK2 and GDH1-CamKK2-CamK4 signaling involved CREB phosphorylation. In addition, combined targeting of RSK2 and GDH1 synergistically induced anoikis in LKB1 wild-type (wt) expressing cells and RSK2 directly phosphorylated LKB1, leading to AMPK activation. These data suggest that RSK2 may signal through LKB1 and AMPK to contribute to anoikis resistance in LKB1 wt cells. Thus, we hypothesize that RSK2 and GDH1 coordinately regulates AMPK and CREB in transcription- dependent and -independent manners to provide pro-metastatic potential in cancer cells. Thus, targeting both cellular and metabolic signaling by combination of RSK2 and GDH1 inhibitors is a promising anti-metastasis therapeutic strategy. We will use lung cancer with LKB1 or LKB1 null as a research platform. Three specific aims are proposed: (1) To demonstrate whether RSK2 and GDH1 coordinately provides anti-anoikis protection to cancer cells by activating AMPK through LKB1 and CamKK2, respectively; (2) To determine whether RSK2 and GDH1 together mediates migratory and pro-invasive signals by activating CREB and CREB transcription targets; (3) To validate whether RSK2 and GDH1 signaling correlates with metastatic potential in patient tumors and evaluate the therapeutic efficacy of targeting RSK2 and GDH1 in combination in treatment of metastatic cancers.